Thermally stimulated discharge current (TSDC) characteristics in β-phase PVDF–BaTiO3 nanocomposites

β-phase polyvinylidene fluoride (PVDF)–BaTiO₃ nanocomposite samples have been prepared by solution mixing method. XRD data represent that the crystallinity of PVDF decreases with increase in loading level of BaTiO₃ nanoparticles. DSC curve represents that the melting point of PVDF is lightly affected by loading concentration of BaTiO₃. The morphology and microstructure of PVDF and PVDF embedded by BaTiO₃ nanofillers were investigated by using inverted contrast microscopy (ICM) and scanning electron microscopy (SEM). FTIR interferrometry is proven that PVDF and BaTiO₃ are not chemically interacting; therefore, interaction of BaTiO₃ is van der Waals type of interaction. The thermally stimulated discharge current (TSDC) of PVDF and PVDF–BaTiO₃ nanocomposites sample was characterized by single peak. The observed TSDC peak is discussed on the basis of dipolar and interfacial polarization.     

Molecularly Imprinted Supermacroporous Cryogels for Myoglobin Recognition

Myoglobin is a primary iron, and oxygen-binding protein of muscle tissues and levels can be an important diagnostic biomarker for acute myocardial infarction, myocardial necrosis, or other cardiac diseases. The establishment of myoglobin recognition systems is important because of its protein’s structural and functional values in physiology, biochemistry, and diagnostic value in some damaged muscle tissue and cardiac diseases. For this purpose, we used molecular imprinting technique for myoglobin recognition from aqueous solutions and human plasma. In the first step, myoglobin-imprinted poly(hydroxyethyl methacrylate) (PHEMA) cryogels (MGb-MIP) were prepared, and optimum myoglobin adsorption conditions were determined. Selectivity experiments have been done with the competitive proteins, and myoglobin adsorption from IgG and albumin-free human plasma was studied. The purity of the desorbed samples was determined with SDS-PAGE. The desorption efficiency and reusability of the MGb-MIP cryogels were tested, and it was shown that without any significant loss in the adsorption capacity, MGb-MIP cryogels can be used a number of times for myoglobin recognition and separation.     

Alteration in Cross Diffusivities Governs the Nature and Dynamics of Spatiotemporal Pattern Formation

Realizing spatiotemporal patterns out of a chemical reaction diffusion system remains an experimental challenge owing to the difficulty in overcoming the stringent condition of diffusion driven instability. Herein, by considering the spatially extended Gray-Scott model system, we have investigated how the cross diffusivities of the reactants involved influence the nature and dynamics of spatiotemporal patterns. Our study unravels that in absence of diffusion driven instability, spatially inhomogeneous patterns can be obtained for the Gray-Scott model system, and unstable time dependent patterns can be stabilized just by adjusting cross diffusivities of the reactants. Interestingly, the effect of cross diffusion in presence of the diffusion driven instability can differentially alter the speed of pattern formation, and potentially modify the nature of the spatiotemporal patterns obtained under different parametric conditions. Experimental verification of our findings may allow us to observe spatiotemporal patterns beyond the regime of classical Turing instability.     

Electrooptic properties of polycrystalline SnSe thin films

It is observed from the studies of electrical resistivity of films of SnSe of different thicknesses and substrate temperatures that resistivity decreases with increase in thickness and substrate temperature. The study of variation in band gap with thickness shows a linear relationship between band gap and 1/t². Finally, band gap – substrate temperature studies show that the band gap increases with substrate temperature.     

Growth of hollow Se–Te whisker crystals

On the basis of micro- and macro-morphological studies the mechanism responsible for the growth of Se–Te whiskers has been suggested. It has been shown that Sc–Te whiskers grow by layer growth mechanism in which screw dislocation is not the source of step but the growth proceeds by two-dimensional nucleation. This has been supported by the supersaturation data. The plausible mechanism for the growth of hollow whiskers has also been suggested.     

Observation of a donor exciton band in silicon

Far-infrared transmission measurements on P-doped Si at donor concentrations below the metal-insulator transition show absorption bands from donor pairs. We identify the lowest energy band as charge transfer excitations from a donor to its neigbhor, forming excitons (D⁺D^-) in the Mott-Hubbard gap. The results suggest that charge transfer states in complexes dominate the low-energy optical excitations as the insulator approaches the Mott density.